My friends co-worker kept talking about drugs and how used to be a huge ass tweaker, and how he can get it anytime for free and shit. Then he asked my friend if he ever does drugs and my friend told him he smokes weed. My friend said He seemed cool(not cool in the normal sense, but as in the it's okay to tell him,), but he's a tweaker, and now i'm thinking it was not such a good idea to tell him. He mentioned if I get hurt on the job they can do a hair test. How can my friend keep his job safe from this guy getting canned?